Power unit



3 Sheetsv-Sheet l L. MELCHER POWER UNIT Filed Jan. 27. 1938 Sept. 10, 1940.

Sept. 10, 1940. 1..w. MELCHER POWER UNIT 3 Sheets-Sheet 2 Sept 10, 1940- l.. w. MELCHER POWER UNIT Filed Jan. 27, 1958` 5 Sheets-Sheet 3 Patented Sept. 10, 1940 PATENT lori-"lcs POWER. UNIT Lee W. Melcher, Waukesha, Wis., assignor to Waukesha Motor Company, Waukesha, Wist, a corporation of Wisconsin Application January7 27, 1938, Serial No. 187,132

12 Claims.- (Cl. 12S- 1) The present invention relates generally to power units. More particularly the invention relates to that type of power unit which is mounted or suspended beneath the bottom of a railway car and comprises an internal combustion engine for driving an electric generator or other mechanism, a battery or set of inclined cylinders'containing liquid fuel under pressure, such for example as propane, and a system forv delivering at a predetermined and uniform pressure fuel vapor from the tops of the cylinders to the engine for operating purposes.

A unit of this type is usually used throughout the year especially when connected to drive an l'electricgenerator, and encounters high as well as sub-zero atmospheric temperatures. When temperatures beneath F. are encountered it has been found in practice that there is not sufficient pressure or vaporization'of the liquid fuel in the cylinders to supply the engine yfor full load operation. y

One object of the invention is to provide a power unit of the type under consideration which is an improvement upon, and is more practical and efficient than, previously designed units of 'like character by reason of the fact that it includes improved means for heating`v the fuelcontaining cylinders whenlow atmospheric temperatures are encountered in order to provide sufficient vaporization of the liquid fuel to meet thel requirements of the internal combustion engine during full load operation. Another object of the invention is to provide a power unit of the 'last mentioned character in which the heating means for the fuel containing cylinders comprises hollow'drums which are arranged in heat exchange relation with the cylinders and have a pipe connection leading to them from the exhaust pipe of the engine and additional pipe means extending between them whereby the exhaust gases or products of combustion emanating from the engine during operation thereof are causedy to flow successively through the drums in order to heat them and cause them in turn to heat the cylinders and `vaporize the 4 is empty and then from the top of. the other cylinder, and the pipe connection and additional Another object of the linvention is to provide apower unit of the type and character last menytioned in which the pipe connection between the drums and the exhaust pipe of the engine embodies a fitting with a branch leading to the drums and a second branch leading to atmosphere and is provided with a butterfly type valve which may be shifted or manipulated back and forth between a position wherein it closes the branch leading to the drums and effects opening of the other branch for the direct passage of exhaust gases from the engine to atmosphere and a position wherein it closes the second branch, that is, the branch leading to atmosphere and effects opening of the branch leading to the drums for the passage or iiow of the exhaust gases through the drums. t

' A further object of the invention is to provide a power unit of the last mentioned character which embodies means for automatically controlling the valve so that the exhaust gases or products of combustion from the engine fiow through the drums when the atmospheric temperature is 20F. or below and flow directly to atmosphere when he temperature of the atmosphere about the unit exceeds 20 F.

A still further object of the invention is to provide a power unit of the type under consideration which is generally of new and improved designv and effectively and efdciently fulfills its intendedv purpose. f

Otherffobjects of the invention and the various advantages and characteristics of the present power unit will be apparent from a consideration of the following detailed description.

The invention consists in the several novel features which are hereinafter set forth and are more particularly defined by claims at the conclusion hereof,

In the drawings which accompany and form a part of this specification o r disclosure and in which like numerals fof refer( .ice denote corresponding parts throughout the several views:

Figure 1 is a fragmentary side elevation of a drums for heating the cylinders and showing in" railway car having applied thereto a power unit embodying one form of the invention;

Figure 2 is an enlarged vertical transverse sectional view on the line 2--2 of Figure l, illustrating the arrangement or position of Vthe internal combustion engine and the liquid fuel containing cylinders. and showing the pipe connection between the cylinderI heating drums and the exhaust pipe of the engine;

Figure 3 is a diagrammatic type View of the system for supplying or delivering fuel vapor from the tops of the cylinders to the carburetor of the internal combustion engine Figure 4 is a vertical transverse sectional View illustrating the -design and construction of the detail the branch equipped fitting in the pipe connection between the drums vand the engine exhaust pipes and also the automatic valve controlling means whereby the exhaust gases or products of combustion 'are controlled sol that they flow to the drums during low atmospheric temperatures and to atmosphere during higher'temperatures, that is, temperatures above 20 F.;

Figure 5 is a, fragmentary sectional view through the cylinder heating drums, showing in detail the design and arrangement of the pipe or conduitlmeans whereby the exhaust gases are caused to flow successively through the drums; and

Figure 6 is a diagrammatic view. of a second or modified form of power unit. l

The power unit which is shown in Figures 1 to 5 inclusive of the drawings constitutes one embodiment of the invention and is illustrated in connection with a railway passenger car C as a medium for driving the generator for supplying electric current to the various electrical embodies a flat bottom c2 which together with sides and a roof or top defines a compartment. The generator for the car C is located beneath the bottom c2 of the car body and has the reference character G applied thereto. The power unit is located or disposed beneath the bottom c2, as shown in Figures 2 and 4, and comprises as the main or essential parts thereof an internal combustion engine 1, a pair of fuel cylinders 8 and 9, a system I0 for delivering fuel from the cylinders to the engine for operating purposes, and a pair of drums II and I2 for use in heating the cylinders for fuel vaporizing purposes during low atmospheric temperatures.

The engine 1 is of standard design and embodies at one side thereof an intake manifold I3 and an exhaust manifold I4. The intake manifold I3 has a carburetor I5 for supplying it with a mixture of ful gas and air and embodies a plurality or set of branches which serve to supply the mixture' into the cylinders of the engine Via valve controlled inlet ports in the cylinder block. The exhaust manifold I4 located above the sintake manifold I3A vand has branches leading from the valye controlled outlet ports in the cylinder block o'f\.the engine. lIn addition it has a discharge or ve ust pipe I6 which extends along one side of the engine and includes a muier I1. The exhaust gases or products of combustion emanating from the engine during operation of the latter flow into the exhaust manifold I4 :and

thence through the muffler equipped exhaust pipe I6 as well understood in the art. The engine 1' is disposed in a transverse position beneath one side of the bottom c2 lof the car body and is` suitably encased and protected by a housing I8. It is connected through the medium of its crank shaft (not shown) to drive the generator G and is suitably cooled by a water jacket and radiator (also not shown). The generator G is located at the inner end of the engine 1 and the casing thereof is bolted or otherwise flxedly securedA to the adjacent portion of the engine. The housing I8 surrounds the bottom and sides of the engine and is provided at 4the upper corners thereof with wheels I9 which are mounted on, and adapted to vtravel over, a pair of parallel laterally spaced tracks 20. The latter are-suitably xed or secured to the bottom c2 of the car body and embody extensible sections 2| which are adapte'd to be shifted outwardly .beneath the adjacent side of the car body and permit the engine and generator to be Wheeled in a horizontal rectilinear course from anl operative'position beneath the bottom c2 into an inspection or repair position wherein they are disposed outwardly and to one side of said bottom.

The fuel. cylinders 8 and 9 are adapted to contain liquid fuel under pressure, such for example as propane. They are mounted. or disposed in a housing 22 and comprise cylindrical side walls 23, bulged or rounded bottom walls 24, and top walls 25. Ihe housing 22 is located in opposed relation with the internal combustion engine 1 and is suitably secured in a suspended manner from the bottom e2 of the car body c. It is adapted to hold the fuel cylinders 8 and 9 in an inclined position with the top walls 25 facing outwards, as shown in Figure 4, and comprises an inclined bottom 26, a back wall 21, and a front wall 28. The bottom 26 is provided with cradles 29 which support the two fuel cylinders .and hold them against lateral displacement. The front wall 28 is hinged at the lower margin thereof so that it may be swungoutwardly and downwardly into an open position. In such position the fuel cylinders are accessible for inspection, control or replacement purposes. The bulged bottom walls 24 ofthe cylinders are disposed adjacent to the lower portion of the back wall 21 of the housing 22 and have rings 30 welded or otherwise fixedly secured to the outer faces thereof. Said rings constitute feet whereby the cylinders may be stood in an upstanding position after removal from tlie housing. The top walls 25 of the cylinders have reduced outwarcy extending cylindrical necks 3| which are closed by plugs 32. These plugs are provided with outlet valves 33 and L-shaped pipes '34. The valves are exteriorly disposed with respect to the plugs and are manipulable for opening and closing purposes when .the front wall 28 of the housing 22 is in its open l position. The L-shaped pipes 34 have short branches 35 and long branches 3B. The short branches are connected and lead to theoutlet valves 33. The long branches 3B are -so arranged that when the cylinders are in their proper or operative position in the-housing they extend vertically and serve to conduct fuel vapor fromv The small pipe 31 leads from the cylinders 8 and 9 and is connected to receive fuel vapor from the cylinder 8 by way of a'flexible tube 39, a`

reverse flow check valve 40, a pressure regulator 4|, anexcess flow valve 4I, a. globe valve 42, a pipe connection 43,' anda T-fitting 44. The flexible tube 39 extends through a hole in the cylindrical neck 3| of the cylinder 8 and is connected to the outlet valve 33 for said cylinder. Under normal working conditions fuel vapor ows from the top portion of the interior of the cylinder 8 through the flexibleI tube 39, the reverse fluid check valve 48, the pressure regulator 4|, the globe valve 42,`the excess flow -valve 4|, the pipe connection 43 and the T-fitting. 44 into the pipe 31. The pipe 31 isV connected to receive fuel vapor from the cylinder 9 by way of a flexible tube 45, a reverse flow check valve 46, a pressure regulator 41an excess flow valve 41a, a globe valve 48, and a fitting 49. Ihe flexible tube 45 extends through a hole in the neck r3| of the cylinder 9 and is connected to the outlet valve 33 of said cylinder so as to receive fuel vapor from the cylinder interior. During use of the unit fuel vapor fiows from the cylinder 9 to the pipe 31 by way of the tube 45, the check valve 46, the pressure-regulator 41, the excess flow`valve 41a, the globe valve 48, and the fitting 49. The pressure regulators 4I and 41 are differently set. For example, the regulator 4| is set at'15 pounds and the regulator 41 is set at.10 pounds. As a result 'of this arrangement gas vapor will first flow from the cylinder 8 through the system to the carburetor I5. As soon as the tank 8 becomes exhausted of fuel, the tank 9 automatically cuts into the system I8 as a result of the operation of the regulator 41 and serves as the fuel supply for the carburetor. The reverse flow check valves 40 and 46 serve to prevent fuel vapor from one cylinder passing to atmosphere in the event that the flexible tube for. the other cylinder ,becomes severed or disconnected. The pipe 38 leads to the carburetor I5 and receives fuel vapor from the pipe 31 by way of a pressure regulator .50, an excess flow valve 5|, and a fuel regulator and automatic shut-olf 52. The pressure regulator is provided with a safety relief valve 53 and is connected to the discharge end of the pipe 31 by way of a fitting havin'g a pressure gauge 54 connected thereto. The excess ow valve 5| is connected to the outlet of the pressure regulator by way of a pipe connection 55 and isA connected to the fuel regulator and automatic shutoff 52 by a flexible tube 56. The outlet of the fuel regulator and automatic shutoff is connected to the inlet end of the large pipe 38. When one of the cylinders is connected to supply fuel vapor to the pipe 31 and the internal combustion engine is started, the vapor passes successively through the pressure regulator 50, the excess flow valve 5I, the fuel regulator and automatic shut-off 52, and the large pipe 38 to the carburetor I5. The carburetor,

, as well understood in the art, serves to mix air with the fuel vaporand form a combustible gaseous mixture which passes through the intake manifold I3\into the cylinders ofthe engine via the valve cbntrolled inlet ports in the cylinder block of the egine. As the result of the action during temperatures below 20 F., and as hereinafter described, to have the exhaust gases or products of combustion emanating from the ex; haust pipe I6 of the internal combustion engine pass therethrough so that they serve to heat and vaporize the liquid fuel in the cylinders. At temperatures below'20" F. there is not suiiicient vaporization of the liquid fuelin the cylinders to supply the engine under full load operation. By heating the cylinders when low atmospheric temperatures are encountered the necessary vaporization of the liquid in the cylinders takes place to create asufficient fuel vapor supply for' engine operating purposes. The two drums are interposed between the bottom walls 24 of the two cylinders and the back 'wall 21 of the housing 22 and comprise dished or concavo convex front walls 51, flat circular rear walls 58,A and cylindrical side Walls 59.-'

The front walls are shaped conformably to and bear directly against the outer faces of the bulged bottom walls 24 and hence the drums are in direct heat exchange relation with the fuel cylinders. The rear walls 58 define with the front 'and side walls gas compartmentsV 60 and are separated from the back walls 21 of the housing 22 by strips 6| of suitable heat insulating material. The Vside walls 59 serve to space apart the front and rear walls of the drums and fit Within the rings 38 on the` bottom walls of the fuel cylinders. The drum is connected to receive the exhaust gases-or products of combustion from the engine exhaust pipe by a pipe` connection .62. The inlet end of this connection has a flared mouth 63 and the outlet end extends through a holev or aperture in the back wall 21 of the housing 22 and is connected to the'rear wall 58 of the drum II. The rear or discharge end of the exhaust pipe I6 fits within the mouth 63 and is adapted to slide into and out of engagement with the latter in re sponse to shift of the engine 1 into and out of its operative position. The drum II is connected to the drum I2 by way of a pipe 64. This pipe extends horizontally, as shown in Figure 5, and is connected at one end thereof to the compartment of the ldrum I-I by way of an elbow and a nipple 66. The other end of the pipe 64 is connected to the gas compartment of the drum I 2 by way of an elbow 61 and a pipe nipple The gascompartment of the drum I2 is connected to atmosphere by way of an exhaust or outlet pipe 69. When the engine 1 is started at any time when low temperatures are encountered, that is, temperatures less than 20 F. and the exhaust gases are permitted to flow from the engine through the pipe connection 62 to the drum such gases pass through the drum- II and thence-to the drum I2 via the pipe 64.

After flowing through Athe compartment 60 of the drum I2 such gases are exhausted to'atmosphere.A by way of the pipe 69. sive travel of the gases through the two drums the fuel cylinders 8 and 9' are heated to such an extent that the liquid fuel in the cylinders l vaporizes sufficiently to form an adequate vapor supply for the engine under full load 'conditions. Because the system I 0 serves to unload the cylinders 8 and 9 in sequence,- i. e., the cylinder 8 first 'and then the cylinder 9, and further, because the exhaust gases pass successively through the drumsII and I2 maximum efciency is obtained. This is attributable to the fact that when the cylinder 8 is unloading most of the heat from the exhaust gases or During succesproducts Vof combustion is absorbed by.such cylinder since such gases or products of combustion ow first into the drum H. When the cylinder 9 is unloading after emptying of the cylinder 8 there is little absorption of heat by the cylinder 8 due to no fuel vapor-ization therein.- Because of the small amount of heatl which is absorbed by the cylinder 8 after emptying of the latter there is su'icient heat in the exhaust gases passing through the drum -12 efliciently and effectively to vaporize the fuel in the cylinder 9. densation from the two drums Il and l2, each drum is provided with a small drain pipe 10. The two pipes 10 are connected to the bottom portions of the drums and extend outwardly through the back wall 21 of the cylinder housing 22.

. In order that the exhaust gases may be directly discharged to atmosphere when the temperature of the surrounding atmosphere is high, that is,-

above 20 F. and-hence suflicient to eiect the necessary vaporization of the liquid fuel in the vcylinders 8 and 9, the pipe connection 62.is provided with a fitting 1l. This tting embodies a pair of branches 12 and 13 and has in the interior thereof a butterfly type valve 14 for controlling the flow of exhaust gases through the ltwo branches. The branch 12 of the fitting leadsto and communicates with the drum l I and. the branch 13 extends downwards and leads to atmosphere, The valve 14 is xed to and radiates from a horizontal pivot shaft 15 and is adapted to swing back and forth between a position wherein it closes the ybranch 13 leading to atmosphere Aand opens the branch 12 leading to the drum Il and a position wherein it closes the branch 12 and opens the branch 13. When the valve 14 is in such a position that it closes the branch 13, the exhaust gases emanating from the internal combustion engine 1 flow through the branch`12 and thence through the drums and produce the desired heating of the cylinders for foel vaporizing purposes. When the valve 14 is in its other position, that is, in such position that the branch'12 is vclosed and the branch 13 is open, the exhaust gases flow directly to atmosphere and hence the heat thereof. does not result in vaporization of the fuel in the cylinders 8 and 9.

The valve 14 is controlled or shifted automatically in response to temperature changes, by way ,of a heat or temperature responsive device 16. 'I'his device is positioned above the fitting 1|, as shown in Figures Zand 4, and comprisesl a bellows 11, a stem 18, an arm 19, and a protective casing 80. The bellows 11 is filled with any suitable readily expansible fluid and is fixed at one end thereof to the top wall of the casing 80. 'Ihe stem 18 is connected to, and extends from, the other end of the bellows and, projects through a hole in the bottom wall of thecasing. The arm 19 is xed to one end of the pivot shaft 15 and is pivotally connected at its distal end to the lower v-end of the stem 18. The bellows is so arranged and designed that when atmospheric temperatures in excess of 20 F. are encountered it ex- 4 pands and through the medium of the stem 18 and the arm 19 operates to hold the butterfly type valve 14 in such a position that it closes the branch 12 and'opens the branch 13 for the direct passage of exhaust gases to atmosphere. When the temperature of the surrounding atmosphere drops to 20 F. or lower the bellows'11 is adapted to contract and operates through the medium of the aforementioned stem and arm toshift the valve In order to permit drainage of con-- into its other position wherein it serves to close the branch 13 and open the branch 12 for the passage of exhaust gases to the drums il and l2.

The device 16 constitutes or exemplifies simple v one of the fuel tanks is connected to supply fuel vapor to the carburetor l5 of the engine and the engine is started, the fuel vapor flows through to the carburetor and after being mixed with air therein passes into the engine, as hereinbefore described.A If the temperature of the surrounding atmosphere is low, that is 20 F. or less,- and there is not sufficient pressure orvaporization of liquid fuel to supply the engine under full load the device '16 functions or operates to close the branch 13 of the fitting 1| and to control theI fitting in such manner that the exhaust gases or products of combustion emanating from the exhaust pipe I6 of the engine flow into the drum l l. From such drumthe gases 'ow into and through the drum l2 and thence to atmosphere and operate during their passage through the drums so to heat the'cylinders as to vaporize the liquid and create sufficient pressure or fuel vapor properly to supply the' engine with fuel under full load or working conditions. In the event that higher atmospheric temperatures are encountered, that is, 'temperatures in excess of 20 F. thev device 16 operates to shift the valve 14 so as to close the branch 12 and open the branch 13 and hence results in the exhaust gases flowing directly to atmosphere Byproviding the drums 8 and 9 and the device 16 for controlling the flow of exhaust gases to the drums .the unit is adapted to operate eiciently when either high or extremely low temperatures are encountered. Under certain temperature conditions, the bellows will maintain the valve 1li in a position wherein the two branches are each part way open. When the.

valve is in such a position, a portion of the exhaust gases will be exhausted to atmosphere and the remainder will ow successively through the cylinder heating drums Il and l2.

The aforementioned power unit eectively and eiiciently fulfills its intended purpose and is characterized by the fact that it is usable throughout the year in places which are subject to wide temperature ranges. The heating means for the fuel cylinders is simple in design and hence may be employed without materially increasing the cost of the unit.

The power unit which is shown in Figure 6 of the drawings is -generally the same as that of for use' in. heating the cylinders 8a and 9a for fuel vaporizing purposes when the rate of vaporization is such that insucient fuel is delivered to the engine for full load operation. The engine has a carburetor l5a and an exhaust pipe IEE, the former being connected to receive fuel vapor from the cylinders Ba and 9 by way of the system I0 and the latterserving as an outlet duct for the pair of outlet branches 12a and 13S.

exhaust gases or products of combustion. The

exhaust pipe Iiia embodies a fitting Ila having a The branch 13EL is controlled by means of a valve 14si and is adapted when the valve is open to discharge the exhaust gases to atmosphere. The branch 12 is connected to the drum -I IEL by way of a pipev 62 and operates when the valve 14is closed to deliver the products of combustion via the pipe 62 to the drum Il. A pipe 84a extends between the drums Ila and l2*at and serves to conduct the products of combustion from the former to the latter. The drum l2a embodies an outlet' pipe 69a and serves as a heater for the cylinder 9a. The valve 14Aa isl controlled automatically by the pressure responsive device 8|. The latter comprises a cylinder 82 and a piston 83. The piston is slidably mounted in the cylinder and is provided with a stem 84 which is connected by an arm 85 to the pivot shaft for the valve 14a. The piston is adapted when reciprocated in one direction b`y the entry of fluid under pressure into the cylinder to open the valve 14a so that the products of combustion emanating from the exhaust pipe are permitted to flow to atmosphere. A compression spring 86 is applied to the piston and operates when the pressure of the fluid in the cylinder decreases to retract the piston so that it closes the valve 14a. The cylinder 82 is connected to receive fuel Vapor from the cylinder 8a by a pipe 81 and from the cylinder ila by a pipe 88. The pipe 81 has .one end thereof connected to the system IIJa at Aa point between the reverse -flow check valve and the pressure regulator for the cylinder 8a and its other end connected to the cylinder 82.

The pipe 88 is connected at one end thereof to the pipe 81 by Way of a fitting 89 ,and has its other end connected to the discharge end of the flexible tube. or hose leading from the cylinder 9e. The pipe 81 includes a reverse iiow check valve 90 at itsinlet end. By Way ofthe pipes 81 and 88 the cylinder 82 is connected to receive `vapor from the two cylinders. When the vaporization of the liquid fuel in the cylinders is suflicient to supply the engine for a full load operation due tonormal or high atmospheric temperature the fuel vapor because of its high pressure develops sucient pressure within the cylinder 82 to move the piston against the force of the spring and.

cause it to hold the valve 14 in its operi position. When 'the valveis in such position the products of combustion'iiow for the most part to atmosphere and but a small amount of exhaust gases, if any, ows through the drums IIB and I2!i due to the fact that the pipe 62B is of smaller crosssectional area than the branch 131; `When low atmospheric temperatures are encountered' and warming or heating action produce more ready vaporization of the fuel in the two cylinders.

Whereas the power unit has been described in connection with a railway car C and as a medium lfor driving the electric generator for the car it is to be understood that the unit may be em-A ployed in other capacities in connection with the drive of other equipment or apparatus. It is also to be understood that the invention is not to be restricted to the details set forth since these may ,heater flxedly secured to the support and (having` a wall arranged so that it is in heat exchange'relie-modified within the scope of the appended claims, without departing from the spirit and scope ofthe invention.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

1. A power unit comprising in combination an engine having an intake manifold and an ex? haust manifold and also having a 'carburetor vconnected to the intake manifold, a supply cylinder adapted to be partially lled with vaporizabler liquid fuel under pressure, means for supplying fuel vapor under pressure from the top portion ofthe interior of the container to the carburetor for delivery to the engine by way of the intake manifold, a hollow heater disposed wholly exteriorly of the cylinder and'having onewallv thereof in heat exchange relation with the bottom portion of saidcylinder, and means for automatically delivering the exhaust gases emanating from the exhaust manifold to the heater when the normal vaporization of the fuel is insuflicient to supply the. engine for full load operation.

2. A power unit comprising in combination an internal combustion engine having an intake ing one wall thereof in heat exchange relation with the bottom portion of said cylinder, a pipe connection leading from the exhaust manifold of the engine and having a fitting therein with a branch communicating with the heater and a second branch leading to atmosphere, a valve mounted in the fitting so that it is shiftable intoQ/ closed relation with either branch, and an autoposed wholly exteriorly of the cylinder and hav- 'a5 matic control device for the valve whereby the 1 valve is shifted soas to close said lsecond branch and open the first mentioned branch of thetting when the temperature of the surrounding atmosphere drops to a predetermined degree and is shifted to close said first mentioned branch and open the second mentioned branch whenl the temperaturerises above such degree.

3. A power unit comprising in combination an internal combustion engine having an exhaust manifold therefor, a support in proximity to the engine, a supply cylinder forv vaporizable liquidV fuel under pressure mounted removably on said support, means operative when the cylinder is in place on the support to supply fuel vapor under pressure from the top portion of the cylinder to the engine for operating purposes, a hollow lation with the cylinder when the latter is in place, and means whereby the exhaust gases emanating from the exhaust manifold during operation of the engine may vbe circulated through the heater in order to heat the cylinder and expedite vaporization of the liquid fuel therein. v

4. A power unit comprising in combination an internal combustion engine having an exhaust manifold, an inclined support, a supply cylinder for vaporizable liquid fuel under pressure, carried by the support in an inclined position and so that it may be readily removed therefrom when emptied, means operative when the cylinder is inplace with respect to -the support to supply fuel vapor under pressure from the` top portion of the cylinder to the engine for op'erating purposes, a hollow heater fixedly secured to the lower portion of the support and having a Wall arranged to abut directly against the cylinder when the latter is in place, and means whereby the exhaust gases emanating 'from the exhaust manifold during operation of the engine may be circulated through the heater in order to heat the cylinder and expedite vaporization of the liquid fuel therein.

5. A power unit'comprising in combination an internal combustion engine having an exhaust manifold, an inclined housing having a door at the top thereof, a fuel supply cylinder for vaporizable liquid fuel under pressure, mounted in an inclined position in the housing and so that it may be removed from the hou-sing upon opening of the door, means operative when the cylinder is in place in the housing to' supply fuel vapor under pressure from the top portion of the cylinder to the engine for operating purposes, a hollow heater ilxecllyA secured in the bottom portion ofthe housing and having a wall shaped con- .formably to the bottom of the cylinder and manifold therefor, a pair of supply cylinders for `y\aporizable liquid fuel under pressure, means operative automatically to supplythe engine first 'with fuel vapor under pressure from the top of one of the'cylinders until such cylinder is emptied and then from the top of the lother cylinder, a

. pair of hollow heaters associated respectively lto the intake manifold, a supply cylinder for vaporizable lliquid fluid under pressure, means for supplying fuel vapor under pressure from the top portion of the interior of the container to the carburetor for delivery to the engine by way ofthe intake manifold, a hollow heater disposed wholly exteriorly of the cylinder and having one walll thereof in heat exchange relation with the cylinder, and means controlled by the pressure of the fuel` vapor for automatically delivering ex- 'haust gases from the exhaust manifold to the heaterwhen the normal vaporization of thefuel is insufficient to supply the engine for full load operation.

8. `In combination, an inclined support, a supply cylinder for vaporizable liquid fuel under pressure, carried by the support in an inclined position and so that it may be readily removed therefrom when empty, means operative when the cylinder is in place withrespectto the support to supply fuel vapor under pressure from the top of the cylinder to a point of use, a hollow heater fixedly secured to the lower portion of the support and having a Wall shaped conformable to the bottom of the cylinder and arranged to abut directly against the cylinder bottom when s the cylinder is in place, and means for flowing a fluid type heating medium through the heater in order to heat the cylinder and expedite vapori- Zation of the liquid fuel therein.

9. In combination, a pair of supply cylinders for vaporizable fuel under pressure, means operative automatically to supply to a point of use fuel vapor under pressure first from the top of one of the cylinders until such cylinder is empty and then from the top of the other cylinder, a pair of hollow heaters associated respectively with and disposed in heat exchange relation with said cylinders, and means for flowing a fluid type heating medium rst through the heater for the one cylinder and then through the heater for the other cylinder.

l0. In combination, a support, a supply cylin- .e

. der for vapcrizable liquid fuel under pressure mounted removably on said support, means operative when the cylinder is in place on the support to supply fuel vapor under pressure from the top portion of the cylinder to a point of use, a hollow heater xedly secured-to the support and having a wall arranged so that it is'in heat exchange relation with the cylinder when the latter is in place, and means operative automatically in response to drop in temperature of the surroun'ding atmosphere to supply a fluid type heating medium to the heater.

l1. In combination, asupport, a supply cylinder for vaporizable liquid fuel' under pressure mounted removably onsaid support, means operative when thejcylinder isin place on the support to supply fuel vapor lunder pressure from the top portion of the cylinder to a point of use, a hollow heater xedly secured to the support and having a wall arranged so that it is in heat exchange relation with the cylinder when the latter is in place, and means controlled automatically lby the pressure of the fuel vapor fo'r'automatically delivering a fluid type heating medium to the heater.

' 12. A power unit comprising in combination an internal combustion engine having an intake manifold and an exhaust manifold andv also having a carburetor connected to said intake manifold, a supply cylinder adapted to be partially filled 'with readily vaporizable liquid fuel under pressure, means for supplying fuel vapor under pressure from the top portion of the cylinderto the carburetor, a hollow heater disposed wholly exteriorly of the` cylinder 'and having a wall thereof conforming to and in direct contact with the bottom portion of the cylinder, and

means Aoperative automatically in response to dropof the temperature' of the surrounding the fuel.

LEE wl MmcHER. 

